291 



number. Both thoracic and anal pseudopocls are present and well de- 

 veloped, both pairs being armed with two circles of claws, those in the 

 apical circle being different in shape, and sometimes in color, from 

 those of the subapical circle. There are no protruded dorsal respira- 

 tory organs such as are present in the aquatic forms in Tanypimc and 

 Chironomincc. The true aquatic forms in this subfamily are easily 

 distinguished from those of the other subfamilies by their snakelike 

 appearance. The pseudopods are absent, and there are no hairs on the 

 body except at the anal end, where there are generally four pairs, which 

 are 'probably sensory in nature. The head is elongate, subconical, in 

 shape ; the antennse are very small and rather rudimentary, apparently 

 consisting of two joints; the mandibles have a slight protuberance on 

 the inner surface near the middle, but no distinct teeth; and the labium 

 is very simple in form and without teeth on its anterior margin. 



In transforming to the pupal stage the terrestrial forms do not en- 

 tirely free themselves from the larval exuviae, the three or four apical 

 segments of the abdomen generally remaining within the skin; but 

 the aquatic pup?e are invariably freed from the exuvi^. 



Pupal Characters 



The pupae of the terrestrial forms may be readily separated from 

 any other Chironomidcc by their distinct spinose armature. The thorax 

 has usually several bristles on the dorsum, while the abdominal seg- 

 ments are invariably similarly armed. The wing cases are slightly sep- 

 arated apically from the sides of the body in some species, but not so 

 distinctly as in the other subfamilies, while in others they are very 

 closely pressed against its side. The last abdominal segment ends in two 

 elongate, conical un fringed processes. The pupaj of the aquatic forms 

 present quite a striking contrast to their snakelike larvae, since all the 

 species as far as recorded have the abdominal segments conspicuously 

 tuberculate, or with small leaflike appendages, as shown in Figure 5, 

 Plate XVII. The thoracic respiratory organs are trumpet- or tube- 

 shaped and rather conspicuous. The last abdominal segment is fur- 

 cate, as in the terrestrial forms, but the branches are divergent instead 

 of parallel. From observations made by Mr. C. A. Hart and the 

 writer it appears that the pupae of the aquatic species are obliged to 

 leave the water to permit the emergence of the imago, and are able to 

 make their way over sand, or other surface, to obtain a solid location 

 for this purpose. During a field trip in April, 19 14, which included 

 visits to various rivers at points in the southern half of the state, ^Ir. 

 Hart and the author found in nearly all these localities large nurnbers 

 of pupae of these aquatic forms floating on the surface of the rivers. 



